External displays are utilized to present content from various computing systems. The display is connected to the computing system with an appropriate interface, such as display port (DP), high definition multimedia interface (HDMI) or video graphics array (VGA). The content to be displayed may be the output of one or more applications running on the computing system, video stored on or received by the computing system, or other forms of media. The computing system may perform any necessary processing on the content in order to present the content on the display.
The display may be a liquid crystal display (LCD). The display typically includes an optical stack, panel electronics, and a backlight. The optical stack is where the content will be presented. The panel electronics receive instructions from the computing system (e.g., a graphics processor, a central processor) regarding the content to be presented and controls the writing of the content on the optical stack and may control the timing associated therewith. The backlight illuminates the optical stack so that the images written thereon can be seen by the user.
The display may include a backlight driver to control the operation of the backlight. In some displays the backlight is on all the time. In other displays, the backlight driver turns the backlight off when the panel electronics are generating an image on the optical stack (image refresh) to mitigate motion artifacts and/or conserve power. When the backlight is on, the brightness of the backlight is typically constant regardless of the content being presented. The backlight is a major source of power consumption in displays where the backlight is always on as well as those where it is throttled off during image refresh.